The hard drive from the flight simulator found in Capt. Zaharie Ahmad Shah's home in Malaysia is now at the FBI lab in Virginia.

FBI computer experts are trying to recover files that were deleted over the past several weeks.

Investigators are looking for any clues that Shah may have used the simulator to plan or practice some kind of some kind of hijacking plot . Sources tell CBS News there is nothing in Zaharie's history to suggest he'd commit a criminal act. But, with radar and satellite data suggesting the jet was deliberately flown off course.

Capt. Zaharie Ahmad Shah, left, and Co-pilot Fariq Abdul Hamid, right, were in the cockpit of Malaysia Airlines Flight 370The FBI is also going through the private computer files of both pilots.

Investigators need some physical evidence, the plane and its data recorders. The wreckage and so-called black boxes may be able to tell us what happened.

But, investigators are not sure where to look.

If investigators can find even a single piece of floating debris from the jet, they will have a chance to narrow the search and find the wreckage. But, if nothing surfaces in the days ahead, investigators could soon face a tough decision as to how long they can continue to look for the missing jet.